Adding Gopher support to MoeNavigatorEngine

I began adding Gopher protocol support to MoeNavigatorEngine. The progress can be viewed in the following ticket at codeberg:

With the current code, the network stack can request resources on a gopher server and read the response from the server. The engine itself needs a "Gopher menu parser" and a "plaint text parser" to be able to transform the response into something that can be rendered. But the mneget tool from the tools collection can already download data via gopher.

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